Sized paper and method of making



p 958 F. A. BROWN 2,330,916

SIZED PAPER AND METHOD OF MAKING- Filed Sept. 8, 1954 STHECH BY M, m, M a I'M (mg/a :ion in the water.

2,830,916 SIZED PAPER AND METHOD OF MAKING Frank Alan Brown, Forest Lake, Iii, assignor to National Dairy Products Corporation, a corporation of Delaware Application September 3, 1954, Serial No. 454,857 5 Claims. (Cl. 1ll7l56) The present invention relates generally to sizing of paper and paper board and, more particularly, it relates to the more efiicient use of starch in sizing paper.

As is well known, paper and paper board are manufactured from fibers which are felted or matted together to form a web. After formation of the web, it is dried, and usually calendered. The resulting sheet, if there have been no additions of sizing agents or other material in the manufacture of the sheet, is quite absorbent and will not resist liquid penetration. An example of the type of sheet is blotting paper and filter paper.

If paper is to resist liquid, so as to become printable and capable of being Written upon with ink, a sizing agent is added in the manufacture of the paper. In this connection, the sizing agent may be added prior to the formation of the Web, i. e., during the preparation of I the fibers, as in the beater, or the sizing agent may be added after web formation. One of the common places of adding sizing is prior to calendering.

Various sizing agents are used and the use of a particular sizing agent is largely determined by the cost of the agent, the desired surface characteristics of the resulting sheet, etc. The more common .sizing agents include rosin, glue, gelatin, latex and starch.

Starch is a highly desirable sizing agent for many purposes, but, up until recently, starch has not been widely used because of its cost in the sizing paper and its use was substantially limited to use in the manufacture of high grade papers. Various types of starches are used in the paper industry, including corn starch, wheat starch and potato starch. The starch has been added during the preparation of the fibers, i. e., to the heaters, and has also been added after web formation, mainly, just prior to calendering. One of the difficulties of adding starch to the heaters is that only a portion of the starch added remains with the formed sheet, thereby making the use of starch even more expensive. However, this difliculty has tended to become less serious with the reuse of the water, i. e., the use of white water, resulting from the manufacture of paper.

The property of starch which makes it so desirable as a sizing agent is not altogether known. While the results of starch sizing are desired, as above pointed out, even better performance characteristics have been sought and substitutes for starch have been and are being tried.

In this connection, various gums and gum-like materials have been tried as a substitute for starch but'these have not provided as good a sheet as starch sized sheets and have been unsatisfactory for various reasons. In this connection, one such substitute agent provides the desired surface characteristics but causes the paper to warp to such a degree as to make the paper unsatisfactory. Another substitute agent showed calcium ion sensitivity, and consequently, it cannot be used in many paper mill operations because of the presence of calcium Still other substitute agents are tacky -or sticky and, as a result, are picked up by the paper making equipment to such a degree as to interfere with the manufacture. As a result, the various gums and gumlike products have not had wide acceptancein the paper industry.

It has been discovered, however, that the amounts of :starch which are used can be substantially reduced by ice the use of carragheen and carragheeniu while at the same time providing a sheet of corresponding quality and providing improvements in the manufacture of paper. On the other hand, through the use of carragheen or carragheenin, larger amounts of starch can be used because of some synergistic action which prevents the starch from becoming tacky. Thus, the carragheen or carragheenin is not used as a substitute for starch but rather is employed as an extender of the starch so that lesser amounts of starch may be employed.

As above indicated, large amounts of starch cause difficulty in the manufacture of the sheet. In this connection, such large amounts of starch cause warping of the sheet or board and picking occurs. Picking is a difficulty which occurs during manufacture ofthe sheet and specifically involves pulling off of surface fibers from the sheet. In the manufacture of sheets sized with large amounts of starch, calender Wrap frequently occurs. This difiiculty involves wrapping of the sheets around calender rolls with resultant breaking of the sheet and interference with the paper machine operation.

The starch-carragheen or carragheenin sizes provide sheets which have excellent printability and in the manufacture of the sheets there is a substantial reduction of tackiness and picking. In addition, the carragheen and carragheenin are not sensitive to calcium ion, and consequently, can be used in practically all types of waters in paper mill operations. Furthermore, this combination reduces warpage of the sheet or board.

The accompanying drawing is a schematic end view of a portion of a sized paper sheet in accordance with the present invention.

Referring now more particularly to the accompanying drawing, a paper sheet is illustrated, having a non-adhesive, sized surface. The sized surface comprises starch in which is dispersed a small but effective amount of a material selected from the group consisting of carragheen and carragheenin.

In the practice of my invention, the carragheen or carragheenin may be added to the heater in paper manulfacture or may be used in surface sizing of the sheet or board prior to or after calendering.

In order to prepare starch for sizing, the starch is made into a slurry and heated to a temperature just below boiling for a period of from 15 to 20 minutes. If carragheen is used, it should be added to the starch slurry and cooked at a temperature above F. for a time not less than about 15 minutes, though it will be understood that at higher temperatures less time will be required. On the other hand, if carragheenin is employed, the carragheenin may be either added during or before cooking of the starch, or it may be added after the starch is cooked.

I have discovered that the sizing agent for application to the paper should contain carragheen or carragheenin in the ratio to starch of from about .01 to 0.15:1 (on a weight basis). While greater amounts of carragheen or carragheenin may be used, additional amounts, relative to the amount of starch, do not provide substantially increased benefits.

The amount of starch employed in the sizing solution, when applied to the web, is from about 4 percent to about 18 percent. The amount of starch empioyed when beater addition of the sizing agent is made depends upon the system in the mill and is usually a function of the amount of make-up water used, or, in other words, the amount of White water use The amount of carragheen or carragheenin which is employed is related to the properties desired, which properties may be those desired in connection with manufacture, as when large amounts of starch are used, or may be particular sheet properties.

As indicated, the particular combination of starch and carragheen or carragheenin which is employed in the paper mill may depend upon the result desired. In general, a manufacturer of paper has a standard for his paper when using starch and when carragheen or carragheenin is employed, the relative amounts of these materials are adjusted to provide a sheet of corresponding characteristics. One of the standards is that of printability and this is largely a visual determination. A sheet is manufactured with starch size, then another sheet is manufactured with the combination of the invention, and. the sheets are compared.

Another test is an oil drip test, in accordance with which a measured amount of oil is placed on a sheet which is inclined and the length of the grease path is measured after a specified time. Still another test in volves the use of a Vanceometer which also measures the effect of dropping oil on a sheet by means of a photo-voltmeter.

A standard test is the amount of light reflected by the sheet and this is a standard test in the paper industry.

With these varied tests, it has been determined that corresponding sheets can be made with substantially reduced amounts of starch when carragheen or carragheenin is combined with the starch. When additional amounts of starch are employed, improved sizing of the sheet can be obtained.

If carragheen is to be employed it may be washed and should be ground. In this connection, the carragheen should be ground to a size smaller than sixty mesh. That is to say, the carragheen should pass through a sixty mesh screen or a finer screen. While larger sized carragheen may be used, such larger particles result in visible specks on the paper.

The carragheenin which is employed may be any one of several available on the market and, for purposes of this invention, the viscosity, gel strength, and suspending power of the carragheenin do not appear to be of substantial importance.

As a specific example, carragheen was harvested from the east coast of Maine and was ground sufficiently to pass an eighty mesh screen. The carragheen was mixed with a starch slurry, the slurry comprising 6 percent starch and .3 percent carragheen, on a weight basis. The slurry was cooked for fifteen minutes at about 200 F. and the resulting sizing was introduced into a water box, the water box being located in a position to apply to the slurry just before it entered the calenders. The slurry was applied in such amount that the sheet had a starch 5 content of 5.35 pounds per ton.

The resulting sheet had a printability equivalent to a sheet in the manufacture of which 8.1 pounds of starch were used per ton. It will thus be seen that the use of a small amount of carragheen replaced 2.75 pounds of starch per ton.

rs another example, carragheen was prepared by harvesting moss and cooking it for twenty minutes at 200 F. in water. The cooking solution was then dried after separation from the fibrous matter. The dried product was mixed with a starch size, after it had been cooked, to provide a solution which comprised .4 percent carragheen and 6 percent starch. The sizing was applied to a sheet just ahead of the calender rolls in an amount equivalent to about 6 pounds per ream. The resulting sheet had printability which was equivalent to a sheet which was sized with a starch 9 pounds per ton, thereby effecting a saving of 3 pounds of starch per ton of paper produced.

As still another example, carragheenin was added with starch at the beater in paper mill manufacture. The stock in the beater had a consistency of 3 percent. A starch slurry comprising 18 pounds of starch was added to the beater and 1 percent of carragheenin was also added, based on the weight of the slurry. Thus, it will said method including the step of extending be seen that when beater additions are made, the starch and carragheenin may be separately added. However, when carragheen is employed at the beater, it must be preconditioned as above specified.

The amount of starch employed per ton will vary but satisfactory results have been obtained at levels as low as 3 pounds per ream. At levels in excess of 18 pounds per ream, the starch does not provide any added advantage.

The term eam, as used in the specification, refers to 530 per sheets which are approximately 24 inches by 36 inches, or 3000 square feet of paper.

In each of the above examples, the use of carragheen or carragheenin resulted in better machine operation. In this connection, less tack was experienced and the amount .der wrap which occurred was reduced. Ene use of carragheenin or carragheen in combination with starch provides more eflicient use of the'starch so that less starch may be used, or, in the alternative, greater amounts of starch may be employed with improved sheet characteristics. The combination of the invention also reduces picking and warping. In addition, calender wrapping is lessened.

The various features of the invention which are believed new are set forth in the following claims.

I claim:

1. A sized paper sheet having a non-adhesive surface, said sheet comprising a paper sheet having incorporated therewith starch and a material selected from the group consisting of carragheen and carragheenin, the ratio of the amount of said material to the amount of said starch being in excess of about .Olzl, said starch being present in an amount of between 3 pounds and 18 pounds per ream of 3,000 square feet of said paper sheet.

2. A sized paper sheet having a non-adhesive surface, said sheet comprising a paper sheet having incorporated therewith starch and a material selected from the group consisting of carragheen and carragheenin, the ratio of the amount of said material to the amount of said starch being in the range of from about .01 :1 to about .15 :l, the

amount of starch per ream of 3000 square feet of said paper sheet being between 3 pounds and 18 pounds.

3. The improved method of sizing paper with starch, the starch by adding a material selected from the group consisting of carragheen and carragheenin to the starch, the ratio of the amount of said material to the amount of starch being in the range from about .01:1 to about .l5:l.

4. The improved method of sizing paper with starch, said method including the step of extending the starch by adding a material selected from the group consisting of carragheen and carragheenin to the starch, the ratio of the amount of said material to the amount of starch being in the range from about .01:1 to about .lSzl, and cooking the starch and said material under conditions which are equivalent to those obtained by cooking said starch and said material at about 200 F. for fifteen minutes.

5. A sized paper sheet having a non-adhesive surface comprising fibers, starch and Irish moss, said Irish moss being washed and ground to a size which is less than mesh, the ratio of said Irish moss to said starch being within the range of from about .01:1 to about .15 :l, and said starch being present in an amount of between 3 pounds and 18 pounds per ream of 3,000 square feet of said paper sheet.

References Cited in the file of this patent UNITED STATES PATENTS 1,799,047 Jones Mar. 31, 193l 2,477,912 Vallandigham Aug. 2, 1949 FOREIGN PATENTS 12,304 Great Britain July 31, 1897 

1. A SIZED PAPER SHEET HAVING A NON-ADHESIVE SURFACE, SAID SHEET COMPRISING A PAPER SHEET HAVING INCORPORATED THEREWITH STARCH AND A MATERIAL SELECTED FROM THE GROUP CONSISTING OF CARRAGHEEN AND CARRAGHEENIN, THE RATIO OF THE AMOUNT OF SAID MATERIAL TO THE AMOUNT OF SAID STARCH BEING IN EXCESS OF ABOUT .01:1, SAID STARCH BEING PRESENT IN AN AMOUNT OF BETWEEN 3 POUNDS AND 18 POUNDS PER REAM OF 3,000 SQUARE FEET OF SAID PAPER SHEET. 